1. Field of the Invention
The present invention relates to a modular molding system. More particularly, the present invention provides a modular molding system which employs fully contained core and cavity modules.
2. Description of Related Art
Injection molding apparatus often employ a pair of die frame assemblies, each of which is configured to receive a die insert therein. When the die frame assemblies are clamped together, the die inserts cooperate with one another to form a molding cavity therebetween. The molding cavity is shaped to form a specific molded part when plastic material is injected into the cavity. In order to mold a different part, the die inserts must be replaced. One such arrangement is shown in U.S. Pat. No. 4,009,979 (xe2x80x9cthe ""979 patentxe2x80x9d, which is incorporated herein by way of reference).
While the use of die frame assemblies does provide some degree of die insert interchangeability, die insert changeovers can be time consuming. By way of example, the location of the ejector pins is typically dictated by the die frame assembly. Thus, the die inserts must be configured such that the ejector pins will properly align with the molding cavity formed by the inserts. Although the ejector pins can often be rearranged on the ejector plate, doing so can be time consuming.
If core lifters are required (such as when the part being molded includes undercuts), the entire die frame assembly (or at least the ejector and retainer plates) often must be changed along with the die inserts. At a minimum, the core lifters must be rearranged on the ejector plate so that they will be properly positioned within the molding cavity. Each of these steps adds considerably to changeover time, and increases molding costs (particularly when die insert changeovers are frequent).
Thus, there is a need for a molding system which expedites changeover time without sacrificing any of the functions and features provided by conventional injection mold tooling.
The present invention provides a modular molding system, comprising:
(a) an upper frame assembly configured for receiving a cavity module therein;
(b) a lower frame assembly configured for receiving a core module therein, the lower frame assembly including a two-stage master ejector system;
(c) a cavity module positioned within the upper frame assembly;
(d) a core module positioned within the lower frame assembly, the core module including a two-stage ejector system having a plurality of ejection elements associated therewith;
wherein the core and cavity modules together define a molding cavity for molding a workpiece therein, and wherein the master ejector system is operable to drive the ejection elements of the core module. The ejection elements may be chosen from the group consisting of ejector pins and core lifters. The master ejector system may comprise first and second master ejector plates, the ejector system of the core module comprises first and second module ejector plates, and at least one of the ejection elements is supported by the first and second module ejector plates. The molding system may further comprise a fluid circuit in at least one of the core module and the cavity module, wherein the fluid circuit is configured such that a fluid may be circulated therethrough. A vacuum circuit may also be provided in at least one of the core module and the cavity module, wherein the vacuum circuit is configured such that a vacuum may be applied to the molding cavity.